On Tuesday evening the 29-year-old lock was one of eight players released from the Six Nations squad for regional action.

But less than 24 hours later the Dragons revealed that a niggle suffered on Wales duty will prevent Coombs, who has played against Italy, Ireland and France, from leading the charge at Ravenhill on Friday evening.

"There was a training session on Monday and he suffered an injury but it's nothing serious," said Dragons director of rugby Lyn Jones.

"It's just a niggle that he needs to sort out so that he is fit against England and Scotland. Andrew needs to relax this weekend to make sure his shoulder is right so that he can create competition for selection."

Coombs, who played the full 80 minutes to help the Dragons upset Glasgow 24-23 at Rodney Parade last Sunday, faces an uphill struggle to feature at Twickenham with Alun Wyn Jones, Luke Charteris and Jake Ball likely to take the second row spots in the squad.

He will no longer get a chance to catch Warren Gatland's eye with an energetic display against the Pro12 title hopefuls in Belfast and Jones will also make a pair of late calls before naming his side.

Fly-half Jason Tovey and number eight Netani Talei are rated as doubtful because of a dead leg and rib injury respectively.

If the former fails to make it then centre Jack Dixon is likely to feature on the bench after nearly five months on the sidelines because of a foot injury.

The Dragons are down to the bare bones in the back three and once again turn to Cross Keys' Rhys Jones at full-back. The Wales Sevens international kicked the match-winning conversion from the touchline in last weekend's tremendous victory against Glasgow.

The back three situation will be eased by the time the region next takes to the field against Connacht at Rodney Parade on March 23 as Hallam Amos and Tom Prydie will be back from ankle injuries, Will Harries will be fit after being concussed last weekend and Dan Evans' ban for a tip tackle will have expired.

Jones is hopeful of heading into a three-week break in fine fettle but acknowledges the size of the challenge that awaits them in Belfast.

"Ulster are the same as Glasgow," said the director of rugby. "They have a talented squad that can carry them through international windows.

"Ruan Pienaar, John Afoa, Nick Williams, these players are not on minimum wage and are signings that the Welsh regions are not in the market for."

Powerhouse number eight Williams, however, will not feature on Friday afternoon after being dropped by Ulster for an "alleged unauthorised absence". BBC Northern Ireland report that the 30-year-old returned to New Zealand last weekend and subsequently missed the province's 14-12 win at Treviso.